A common disadvantage of the known light guiding systems used for motor vehicle lighting devices is the fact that some of the light emitted by the light sources is either not used or the desired shape of the output surface of the light guide does not allow the effective use of the light emitted by the light source. In any case, this reduces the luminous efficiency of the light guiding system. Thus, in the field of the construction of light guides and light guiding systems, it has been a constant concern to propose solutions that will increase luminous efficiency and ensure the homogeneity of the output light beam.
Documents U.S. Pat. No. 6,766,078B, US20170038518A1, EP1085253A3, DE1990464464, EP1867913B1, US20060234612A1, US20150362660A1, WO2017068309A1, DE102005011760B4, DE4129094B4, US20070139955A1 disclose different solutions with two or more light guides in which it is impossible to provide direct or sufficient power supply to each of the light guides.
Patent application CZ 2016-176 discloses a lighting device which comprises a plurality of light sources to meet the output characteristics of two different signal functions. The individual signal functions are provided by means of two different light beams, namely a first light beam emitted by a first optical segment and a second light beam emitted respectively by a light guiding optical segment. The light guiding segment is realized as a flat-shaped light guide which is in its central part provided with a stepped surface, wherein reflective surfaces for directing the light rays already coupled in the desired direction alternate with the secondary input surfaces for coupling the light emitted by the first/another optical segment.
A common disadvantage of the above-mentioned solutions is the fact that they do not allow to provide indirect power supply to two or more light guides arranged in a row next to each other.
When the need arises to transmit light rays from a light source to different separate light guiding segments, one of the arrangements used today is, for example, the positioning of light guides immediately one behind the other, nevertheless, this poses higher demands for built-up space and also causes non-homogeneity of the illumination when viewed from directions other than the X-direction of the vehicle. Another solution commonly used is shaping the light guide with the power section bent so that the light guides can be situated next to each other. This solution, however, involves increased light loss in the shaped parts, since in most cases it is necessary to change the shape within very small distances and this leads to a considerable curvature of the light guide surface, where the light is no longer guided inside the light guide by means of the so-called total reflection, but it penetrates through the walls of the light guide outside the light guide. Another disadvantage is that the parts of the light guide shaped in this manner need to be masked by a cover mask because adjusting the illumination homogeneity is more difficult.
The present invention aims at solving the problem of ensuring effective power supply to different light guides in cases when there is a need to illuminate the area of a light function with required characteristic of the output light beam by means of two or more light guides, preferably located parallel to each other, whereby it is not possible to ensure direct (separate) power supply to each of the light guides, for example because of restricting built-up space, or because of the requirement to minimize the PCBs in the lighting device, etc.